Because we don't want to repeat the mistake of interning Muslims the way the Japanese were interned during WWII.
Now that I have said that, I would like to point out something that doesn't get talked about very much or rather doesn't get talked about enough, the patriotism of the Japanese American in those internment camps. The most decorated units in WWII was made up almost entirely of Japanese Americans who left their families inside those camps and went off to fight for the country that had placed them there.
Imagine if you and your family were rounded up your homes and business taken away, place under military arrest, sent to a camp surrounded by barbed wire and machine guns, by our government and you are given a choice, stay in relative safety and wait for the end of a war, or leave the ones you love locked up by the government and fight for those that would keep you locked up as well.
CAIR doesn't deserve to breathe the same air as the Japanese American patriots that PROVED they were AMERICANS first with the lives, their blood and their heroism. And they certainly don't have the right to complain about how they are treated in this country during time of war, since they have done nothing to defend it from the islamofacists.
Imagine how every morning, American Boy Scouts raised the Flag as the families that remained interned saluted it, while their husbands, sons, and brothers fought fiercely for the country that placed them there.
Now compare the words of CAIR with the actions of real patriots.